Tone arm positioning mechanism



Feb. 13, 1951 J. L. D. MORRISON ET AL TONE ARM POSITIONING MECHANISM 2Sheets-Sheet l Filed Deo.

Feb 13, 1951 J. l.. D. MoRRlsoN ET AL 2,541,826

TONE ARM POSITIONING MECHANISM Filed Dc. 2o, 1945 2 sheets-sheet 2Patented Feb. 13, 1951 2,541,826 TONE ARM POSITIONING MECHANISM James L.Donaldson Morrison and Walter Miller, Benton Harbor, Mich.

Application December 20, 1945, Serial No. 636,126

8 Claims.

The present invention relates to automatic adjusting means for selectingthe proper place for setting down the tone armon a record in a drop typerecord changer, in accordance with the size of a record which has lastbeen dropped on a turntable.

There are ordinarily two sizes of records used on phonographs; ten (10)inch and twelve (l2) inch. Early in the development of record changers,the tone arm set-down mechanism was adjusted manually for the size ofrecord'being used. Later, automatic adjusting devices were introduced.In the drop type recordchangers, a common form of these automaticdevices comprised a lever which projected upwardly from the base of thephonograph and was arranged so that ten (10) inch records missed it asthey dropped to the turntable, but twelve (12) inch records would strikeit, whereupon the lever moved mechanism provided within the base tochange the setting of the tone arm turning means from a teny 10) inchset down operation to a twelve (l2) inch set down operation.

The present invention is an improvement on these automatic devices, inthat the present device is entirely contained within the tone arm, andis much simpler in construction. The operation of the turning meansunder the base always turns the `tone arm shaft to the same angularposition for setting down the tone arm on a record, but if a twelve (12)inch record is dropped it strikes a feeler lever on the side of the tonearm, which operates a simple lost motion device between the tone arm andits shaft to shift the relative location of the needle just one inchradially further away from the center of the record turntable than isobtained in the normal operation for ten (10) inch records. This feelerlever is so located that a ten (10) inch record misses it and the lostmotion device does not come into play, maintaining the proper set downadjustment for a ten (1G) inch record.

The principal object of the present invention is to provide a sensingand adjusting mechanism contained entirely in the tone arm for properlysetting down the tone arm in accordance with the size of a record beingused. Y

Another object of the present invention is the provision of a feelerlever extending from the side of the tone arm which will'be struck by atwelve (l2) inch record when dropped to the turntable for changing therelative position of the needle to bring it down in the proper startingposition for the twelve (12) inch record with the same angular positionof the tone arm shaft as for a ten (10) inch record.

Another object of the present invention is to 'provide the tone arm witha lost motion device between the arm and its turning shaft for movingthe relative position of theneedle one inch ra- LSU dially further fromthe center of the turntable, in response to the operation of a feelerlever extending from the side of the tone arm sufficiently to be struckby a twelve (12) inch record but not by a ten (l0) inch record so as toeffect a proper set down location for the needle regardless of the sizeof a record to be played.

Other and more specific objects of this invention will become apparentas the description of an illustrative form of device made in accordancewith theY present invention proceeds, having reference to theaccompanying drawing, wherein:

Figure 1 is a fragmentary plan view of the tone arm incorporating thepresent device. Y

Figure 2 is an inverted side view of the top of the tone arm post underthe tone arm shell.

Figure 3 is a partial sectional View taken at 3 3 in Figure/1 partsbeing shown fragmentarily.

Figure 4 is an enlarged detail View taken at 4-#3 of Figure 3.

Figure 5I is a view taken on the line 5--5 of Figure l.

. Figure 6 is a perspective view of the device showing the relation ofparts providing lost motion in the mechanism between the tone arm andthe tone arm post. Y f

Referring to the drawings, the tone arm shell il) is hingedly mounted bya pin Il on the plate E2 which is rotatably mounted on sleeve I3 whichis xed on the hollow tone arm turning post lf3 by means of a set screwI5. The sleeve and post assembly is rotatably mounted in the base I6 bymeans of bearing Il. The base has a cut out groove i8 and the sleeve i3has a tongue I9 extending into the groove for limiting the turningmovement of the sleeve and post assembly to a suitable range determinedby the extent of the groove.

A collar 2l) is adjustably mounted at the top of the sleeve i 3 and hasopposed adjusting screws 2| and 22 acting against opposed surfaces 23and 2d on the sleeve i3, for relative angular adjustment between thecollar and sleeve. An arm25 extending from and iixed to the collar isconnected thru a lostv motion device to the plate I2, for turning thetone arm in response to turning of the post lli. A pin 2'5 passesthrough the hollow post it for lifting the tone arm on its hinge bymechanism operated within the base in a well. rlhe lost motion deviceconnected between the plate l2 and the arm 25 comprises a bell crank 2'!pivotally mounted at 23 on plate l2 and having an I2, and is urged byspring -31 into inoperative position against the pin 38. Itis operatedby the feeler lever 39, also pivoted on the pin 36 and having an arm 48acting against the lug 35. The spring 31 is held in assembly by a iiangeon the head of pin 36, and bears against lug 35 and pin 38 to normallyhold the cam 32 against the pin 38, which is fixed to plate I2. Whenrecords are removed from the turntable feeler lever 39 is free to liftup and let them pass; then to rise to the position shown in solid linesFigure 5. This is possible because feeler lever 39 is freely rotatablymounted on the pin 38, and normally assumes the position shown in fulllines in Figure 5 because of the weight of its feeler causing it to keepits arm 49 up against the lug 35.

In normal operation, the cam surface 33 permits bell crank 21 to be heldby its spring 39 in the position shown in full lines in Figure 1, withvits arm 29 resting on the stepped portion 4I of the arm 25, which isurged against said arm by the spring 3I, one end of which is attached toplate I2, the other end to arm 25. Thus a resiliently held angularrelation is established between the collar 28 and plate I2. Adjustingscrews 2l and 22 are used for fixing the angular relation between thecollar 29 and sleeve I3 and turning post I4, which is xed thereto by setscrew I5.

The adjustment of these screws 2i and 22 is made such that the tone armwill be properly set down with respect to a inch record, when the bellcrank 21 and arm 25 are in the position shown in full lines.

Now, when a 12 inch record is dropped during 5 the record changingoperation, its edge strikes the feeler lever 39 which turns cam 32 untilthe shoulder 34 catches over the side of the arm of bell crank 21. Inthis operation the bell crank bar is turned to the dotted line positionshown in Figure 1, where the arm 29 has been moved off the stepped.portion 4I of arm 25. The stepped portion 4I is followed by an angularportion 42 and a at portion 43.

When the pin 26 is operated to raise the tone arm off its rest and postI4 starts turning to the set down position for the tone arm, the spring3l draws the arm 25 toward the bell crank, raising the arm 29 of thebell crank to slide down the angular portion 42 of the arm 25 and thusturn the bell crank suiiiciently to release the catch shoulder 34,whereupon the cam 32 and its operating lever 39 return to their normalposition. In the meantime the new angular relation between the collar 23and plate I2, caused by the arm 29 being moved to the at portion 43 ofthe arm 25, is held so as to properly position the tone arm for settingit down on the 12 inch record with the same set down angle of theturning post I 4 as for a 10 inch record. In other words, the lostmotion taken up angularly between the arm 25 and plate I2 due to theshift of the bell crank from the stepped portion 4I to the flat portion43, is equivalent to a dilference in set down position of the needle onthe end of the tone arm of 1 inch in radiall distance from the center ofthe turntable. Thus with the ball crank arm 29 on the flat portion 43 ofarm=25 the set down operation is performed when the playing needle is aninch further away from the center of the disc for a 12 inch record thanfor a 10 inch record.

When a 12 inch record has been played and the record changer mechanismraises the tone arm and carries it to its outrnost position the tongueI9 strikes the right end of stop groove I8, as seen in Figure 4, beforethe driving mechanism has stopped rotating the shaft I4 with members I3,2l] and 25. The hinge body I2 is forced to come to a stop but the collar29 and arm 25 along the sleeve I3 continue to turn for a few moredegrees until the bell crank 21 has reengaged the stepped portion 4I asa result of the tension of spring 39, the lost motion mechanism havingbeen returned to the position required for ten inch records. The lostmotion mechanism retains this relation, whereby the tone arm is broughtrelatively closer to the center of the turntable, until a 12 inch recordis again dropped during a record changing operation, to operate thefeeler arm 39, to turn the cam 32, to rock the bell crank 21 out of itslocked engagement with the stepped portion 4i, to permit spring 3 tomove the tone arm relatively fartherrfrom the center of the turntablewhen the usual controls move it into starting position over the record.

Although only one form of the device constructed according to thepresent invention is shown, various modifications in form andarrangement of the parts may be mad-e without de-s parting from the'spirit and scope of this invention.

What is claimed is:

1. In an automatic record changing device for normal size records, meansfor automatically adjusting the set down position of the tone arm forlarger size records comprising, a feeler on said tone arm positioned tobe struck by a larger size but not by the normal size record as it isdropped onto the turntable, and resilient means in said tone armreleased by said feeler to shift the tone arm angularly on its supportan amount sufficient to shift the set down position of the tone arm inaccordance with the size of the larger record.

2. In an automatic record changer, a tone arm, means for automaticallypositioning said tone arm in proper set-down position for playing twosizes of records indiscriminately arranged a stack, comprising a feelermounted ony said tone arm positioned so as to be struck only by a largersize record as it is moved to the turntable, means for properlypositioning said tone arm for the smaller records, a lost motionmechanism in said tone arm operative angularly between said tone arm anditsl support, latch means for normally holding said mechanism inineffective position, and means operated by said feeler in response toits being struck by a large record for releasing' said latch meanswhereby to render said mecha nism effective to shift said ton-e armangularly with respect to its support sufficiently to shift its set-downposition to match the larger record.

3. A lost-motion mechanism in a tone arm for angularly shifting saidtone arm with respect to its turning post, latch means for normallymaintaining said mechanism ineffective, a feeler device on saidtone armextending into the path of a large record being moved to a turntable,and means connected for operation by said feeler in response to thepassing of a large record to release said latch means, and render saidlost motion mechanism eiective.

4. In a record changer, a turntable, a tone arm for playing two sizes ofrecords indiscriminately arranged, said tone arm operated automaticallyto a normal set down position for the smaller records, a feeler on saidtone arm extending into the path of the larger records when moved tosaid turntable, and means in said tone arm operated by said feeler forshifting the angular position of said tone arm with respect to itssupport to position it in proper set down position for the largerrecord.

5. In a tone arm operating means, a turning post for automaticallypositioning said tone arm, a lost motion mechanism between said post andsaid tone arm, latch means normally cocked for holding said lost motionmechanism against operation, and a feeler on said tone arm extendinginto the path of a large size record for releasing said latch means toshift the position of said tone arm in accordance with the large record.

6. In a tone arm operating means, a turning post for automaticallypositioning said tone arm, a lost motion mechanism between said post andsaid tone arm, latch means normally cocked for holding said lost motionmechanism against operation, a feeler on said tone arm extending intothe path of a large size record being dropped to the turntable forreleasing said latch means to shift the position of said tone arm inaccordance with the large size record, and means responsive to turningmovement of said turning post past the position where it moves said tonearm to a position of re'st out of the Way of the records for recoqkingsaid latch means.

7. In a tone arm operating means, the combination dened in claim 6,wherein said responsive means includes a stop for said tone armoperative before said tone arm turning means stops turning.

s A 8. In a tone arm operating means, a yturning post for automaticallypositioning, said tone arm, a lost motion mechanism between said postand said tone arm, latch means normally cocked for holding saidlost-motion mechanism against operation, a feeler on said tone armextending into the path of a large size record being dropped to theturntable for releasing said latch means to shift the position of saidtone arm in accordance with the large size record, and means responsivemovement of said tone arm operating means to turn said tone arm clear ofsaid turntable to recock said latch means.

W. MILLER. i

JAMES L. DONALDSON MORRISON.

REFERENCES CITED The following references are of record in the le ofthis patent:

Johnson Apr. 9, 1946

